Undulating Pipe Manufacture

ABSTRACT

A method for creating lengthwise extending lengths of pipe having an undulating or helical configuration symmetrically formed about a centerline of the pipe includes the steps of heating a sheet of material, feeding the sheet progressively to a succession of stamping stations at which an undulating shape is progressively imparted to the material until at the final station the desired final configuration is achieved in a lengthwise extending half section of the finished pipe, and securing one half section of pipe to another half section of pipe along lengthwise extending edges thereof to form the finished pipe. The undulating pipe of helical configuration finds particular use in the formation of pipelines intended to convey slurries of material such as bituminous material mined from oilsands. Apparatus for carrying out the method is also provided.

This application claims convention priority on Canadian Patent Application No. 2,554,338 filed on Jul. 27, 2006.

The present invention relates in general to the manufacture of elongated lengths of pipe and in particular to the manufacture of undulating pipe used for the transport of solids in a liquid, such as a slurry.

BACKGROUND OF THE INVENTION

Elongated lengths of pipe, connected together to form a pipeline, are used for the transportation of liquids or fluids, such as oil or natural gas from a well to a processing plant and from the processing plant to distribution centers for distribution to consumers. Oil can be extracted from the earth as a liquid, as from a well drilled into the earth. Oil can also be extracted from the earth in processes other than from wells, as for example from the oilsands of northern Alberta. A multitude of different processes have been proposed for extraction of the valuable oil deposits from the oilsands and, once extracted, for the transport of the raw material to a plant for further processing.

Mined oilsands are comprised of coarse sand particles coated with a thin film of water, with oil filling the interstices and minute particles of clay and minerals distributed within the water sheaths. A pipeline presents the most economical apparatus for transporting the mined oilsands to a processing plant. However, a plain pipeline is not particularly efficient for such transport since the slurry contains not only fine particles but large clumps of agglomerated material and that material causes substantial wear on the pipe. It is desirable to be able to control the flow of the slurry in order to prevent or at least substantially reduce contact between the solids within the slurry and the walls of the pipe. Preferably the slurry should be controlled within the pipe so that the solids are entrained in the central or axial position within the pipe rather than adjacent the pipe walls

U.S. Pat. No. 1,451,272 describes a delivery pipe for dredging operations, having internal ribs to keep particles in suspension. A disadvantage to that apparatus is that there can be numerous plug-ups or jamming of the solids with the ribs. In order to keep the flow moving within the pipe it was necessary to pump the slurry at very high flow rates, with attendant high energy costs. There was also unacceptable abrasion wear within the pipe.

United States published patent application No. 2004/0134557 of Jul. 15, 2004 describes another form of pipeline for the transport of mined oilsands over a great distance, That United States patent publication suggests a static undulating conduit which hydrodynamically operates to maintain the solids in suspension, generally within the central area of the pipe cross-section, while avoiding the high velocity of prior art pipe designs and diminishing solids contact and abrasion with the pipe wall.

The pipe or conduit of the published application does not utilize spiral ribs within the conduit to cause the swirling action to keep the solids in suspension. Instead, the published application suggests that the entire conduit should have a spiral configuration designed so that the particles in the slurry will be thrown into the center of the pipe during transportation, thereby keeping the abrasive particles spaced from the pipe walls. By keeping the particles spaced from the pipe walls the effects of abrasion on the pipe walls is greatly reduced, meaning considerably less wear while enhancing the conditioning of the slurry during transport and decreasing the power required to move the slurry along the pipe.

SUMMARY OF THE INVENTION

The pipe of the aforementioned published application is a complex three-dimensional creation having the appearance of an undulating, spiral or helical conduit. It is very difficult to form such a pipe from a length of existing straight pipe. The present invention teaches a method of manufacturing such a pipe based on the principles of a stamping press using appropriately designed male and female die sections.

In particular the present invention would be used as an adjunct to a steel processing plant. Steel sheet material of an appropriate thickness would be delivered continuously from a steel mill in a white hot condition, into the processing equipment of the present invention. That equipment would entail an extended set of male and female dies in a stamping press, the dies being designed to progressively impart a three-dimensional undulating shape to the material as it moves through the press. As it leaves the progressive stamping process the material would form either the upper half or the lower half of a pipe, the upper and lower halves being mirror images of each other. Once the pipe section has cooled the upper and lower halves would be brought together and connected to each other along a seam line that follows the undulations created during the stamping process. If there is no need to separate the upper and lower sections at a later point in time then the sections could be welded together along the seam line. Since the stamping operation will result in the natural formation of a laterally outwardly extending flange along the seam lines of each section it will likely be necessary to trim that flange back somewhat prior to the welding operation. Depending on the size of the pipe the welding operation could be conducted either inside or outside the pipe, the resulting pipe having a generally cylindrical configuration at any cross-section thereof. Flanges could be welded to the ends of any length of pipe so that such lengths could be connected end-to-end to form a continuous pipeline.

If there is any foreseeable need to separate the upper and lower sections at a later point in time, whether for inspection, repair or replacement, then welding would not be the preferred connection method. Use could then be made of the laterally outwardly extending flanges along the seam line of the upper and lower sections, with bolts being used to secure those flanges together, and with a suitable gasket material positioned between the flanges to prevent leakage from the seam. Other connection means available to anyone skilled in the art could be utilized to achieve a separable joint between the upper and lower sections.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a general view of a pipe length having undulations therein, essentially as described in the aforementioned United States published patent application.

FIG. 2 shows the principles of the stamping process according to the present invention.

FIG. 3 shows a side view of an undulating pipe formed in accordance with the invention.

FIG. 4 is an end view of an undulating pipe formed in accordance with the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 illustrates a conduit 10 formed to a shape in accordance with the aforementioned United States published patent application. The conduit 10 has a generally circular configuration at any transverse cross-section but in elevation the pipe has an undulating or sinusoidal appearance with sections A, C, E, etc extending vertically above the pipe centerline X, such sections alternating with sections B, D, F, etc extending vertically below the pipe centerline X. Not only are there smooth vertical undulations but there are also horizontal undulations which extend sideways of the centerline and merge smoothly with the vertical undulations giving the pipe or conduit a spiral or helical effect over its length. This spiral shape will achieve the desired flow pattern with the solids of the slurry flowing generally along the center of the pipe without contacting the inner walls of the pipe in the areas of the undulations. It will be appreciated that this configuration will be difficult to manufacture without the efficient process of the present invention.

FIG. 2 illustrates the apparatus of the present invention in a generally schematic manner. A female mould or die half 12 is formed to the desired configuration and is held stationary in the apparatus of the invention. A male mould or die half 14 complementary to the female mould is also formed to the desired configuration and is fixed to the movable portion of a progressive stamping die. A sheet 16 of white hot steel enters the apparatus from one end, moving from one station to the next along the length of the apparatus. At each station a stamping movement is imparted to the movable male portion of the die so that the steel is imparted with a three-dimensional form that progressively, from station to station, takes on the desired configuration of the undulating pipe. It will be appreciated that the undulating form cannot be created with a single stamping as the shape is too complex for a single stamping. However, at each station the material will take on more of the desired shape with each additional stamping movement. At the end of the apparatus the length of material will have the shape of one lengthwise extending half of the length of pipe, either an upper half or a lower half, it being noted that the upper and lower halves will be mirror images of each other.

Once the formed pipe sections have cooled sufficiently the upper and lower halves 18, 20 are brought together and connected along the longitudinal edges thereof as shown in FIG. 3. If there is no need to later separate the upper and lower halves, then they can be welded along the abutting edges of the halves, for example along the seam line 22. That line will follow the undulations. The weld can be created along the outside of the pipe or, if the pipe is of a large diameter, along the inside thereof. As seen in FIG. 4 there will be a naturally formed laterally outwardly extending flange 24 at each edge of the upper and lower halves 18, 20, which flange provides a good base for the weld. Prior to welding it may be necessary to trim the flanges back closer to the upper and lower halves so as to achieve a proper weld without extraneous material being involved.

While FIG. 3 illustrates a weld to connect the sections together it will be appreciated that, as indicated above, other connection mechanisms can be utilized. If the upper and lower sections are to be connected together in a fashion such that they can be separated for the purpose of inspecting the pipeline interior, for repair of a section, or for replacement of a section, then the longitudinally extending joint between the sections should include an appropriate gasket (not shown) to seal the joint as much as possible so as to prevent leakage during operation. With reference again to FIG. 4, it would be possible to secure the upper and lower halves or sections together by passing a plurality of longitudinally or lengthwise spaced apart bolts, machine screws, or rivets (not shown) through the flanges 24. Such securing means would be aligned for example with the indicated lines Y shown in FIG. 4.

A flange can be welded to each end of the pipe, as is well known in the pipeline art, to create a means for connecting lengths of pipe end to end in a conventional fashion, so as achieve a pipeline of any desired length. 

1. A method of forming a length of undulating pipe having a centerline and a lengthwise extending generally helical configuration symmetrically formed about said centerline, comprising the steps of: providing hot stamping apparatus consisting of a plurality of stamping stations, each station including a stationary female die half and a movable male die half, each die half having a configuration for progressively forming lengthwise extending half sections of the finished pipe; heating a sheet of material from which said pipe is to be formed; feeding said heated sheet of material into said apparatus from station to station to progressively form said helical configuration until the desired helical configuration in the lengthwise extending half section of pipe is achieved at a final stamping station; repeating said heating and feeding steps in order to create a plurality of identical lengthwise extending half sections of pipe, each said half section having a pair of lengthwise extending edges; and abutting one of said half sections of pipe to another half section of pipe along the respective lengthwise extending edges and securing such half sections along said edges thereof to create said length of undulating pipe.
 2. The method of claim 1 wherein said sheet of material is a sheet of steel.
 3. The method of claim 2 wherein each said half section of pipe is formed with an outwardly extending flange along each such lengthwise extending edge and said securing step includes the step of welding adjacent and abutting flanges together.
 4. The method of claim 1 wherein each said half section of pipe is formed with an outwardly extending flange along each such lengthwise extending edge and said securing step includes the step of clamping adjacent and abutting flanges together by a plurality of fasteners spaced apart along such flanges.
 5. The method of claim 4 wherein said fasteners are selected from the group of fasteners consisting of rivets, machine screws, and bolts and nuts.
 6. The method of claim 5 including the step of positioning a sealing gasket between adjacent flanges prior to said securing step.
 7. The method of claim 1 including the step of forming a radially extending flange at each end of a finished pipe for fastening one length of finished pipe in end-to-end fashion with another length of finished pipe.
 8. Apparatus for forming a length of undulating pipe having a centerline and a lengthwise extending generally helical configuration symmetrically formed about said centerline, comprising: furnace means for heating sheets of material from which said pipe is to be formed; a plurality of stamping stations, each station including a stationary female die half and a movable male die half, each die half having a configuration for progressively forming lengthwise extending half sections of the finished pipe; means for feeding a heated sheet of material from said furnace means to a first stamping station and then to successive stamping stations until at a final such station the lengthwise extending half section of the finished pipe having the desired configuration is formed; and means for bringing one lengthwise extending half section of the finished pipe into abutting contact with another lengthwise extending half section of the finished pipe along respective lengthwise extending edges thereof for securing the half sections together along the edges thereof to create the finished pipe. 